Antarctic warming greater than expected

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NEW YORK — New research suggests that West Antarctica has warmed much more than scientists have thought over the last half-century, an ominous finding given that the huge ice sheet there may be vulnerable to an eventual collapse, with potentially drastic effects on sea level.

A paper released Sunday by the journal Nature Geoscience found that the temperature at a research station in the middle of West Antarctica has warmed by 4.4 degrees since 1958. That is roughly twice as much as scientists thought and three times the overall rate of global warming, making central West Antarctica one of the fastest-warming regions on Earth.

‘‘The surprises keep coming,’’ said Andrew J. Monaghan, a scientist at the National Center for Atmospheric Research in Boulder, Colo., who took part in the study. ‘‘When you see this type of warming, I think it’s alarming.’’

Warming in Antarctica is a relative concept. West Antarctica remains an exceedingly cold place, with average annual temperatures in the center of the ice sheet that are nearly 50 degrees below freezing.

But the temperature there does sometimes rise above freezing in the summer, and the new research raises the possibility that it might begin to happen more often, potentially weakening the ice sheet through surface melting.

A potential collapse of the West Antarctic ice sheet is one of the long-term hazards that have led scientists to worry about global warming. The base of the ice sheet sits below sea level, in a configuration that makes it especially vulnerable.

Scientists say a breakup of the ice sheet, over a period that would presumably last at least several hundred years, could raise global sea levels by 10 feet.

The new research is an attempt to resolve a scientific controversy that erupted several years ago about exactly how fast West Antarctica is warming. With few automated weather stations and even fewer human observers in the region, scientists have had to use statistical techniques to infer long-term climate trends from sparse data.